System for suture anchor placement

ABSTRACT

A system for suture anchor placement includes an apparatus having a handle portion and an operating portion. The handle portion includes a spring, a needle park, and a member for releasably holding a length of the suture. The operating portion includes a sheath tube and a plunger rod slidably disposed within the bore of the sheath tube. The plunger rod is fixedly mounted at its proximal end to the handle. The suture anchor is releasably engaged to the distal end portion of the plunger rod. The sheath tube is mounted to the handle and movable with respect to the handle between a distal position and a proximal position, the sheath tube being resiliently biased to the distal position by the spring and movable to the proximal position in response to proximally directed force of sufficient magnitude applied to the distal end of the sheath tube. The sheath tube has a portion with an outer diameter greater than the diameter of the hole in the bone such that when the installation tool is pressed toward the bone, the sheath tube retracts into the handle and the suture anchor is advanced into a hole previously made in the bone. The suture, initially held in a taut configuration, is released in response to movement of the sheath tube to its proximal position.

This is a continuation of U.S. application Ser. No. 08/725,158 filed onOct. 3, 1996 now abandoned.

BACKGROUND

1. Technical Field

The present disclosure relates to a suture anchor installation systemand, more particularly, to a system for preparing a hole in hard tissueto receive the suture anchor and for insertion therein of a sutureanchor.

2. Discussion of Related Art

During surgery, it is often necessary to attach muscle tissue orprosthetic implants to hard tissue such as bone. Suture anchors are usedin the art to facilitate such attachment by securing a suture to bone.Generally, an anchor is implanted into a hole pre-drilled into a bonemass. A suture engaged by the suture anchor extends from the bone and isused to stitch the muscle tissue or prosthetic device to the bone.Suture anchors find particular use in joint reconstruction surgery,especially during attachment of ligaments or tendons to bones in theknee, shoulder, and elbow.

Several systems have been proposed in the art to aid the surgeon inimplanting a suture anchor into a bone. One such system, shown in U.S.Pat. No. 5,100,417 to Cerier et al., includes a driver having a handleand elongated shaft. An anchor snap fits on the end of the shaft over ananti-rotation pin which mates with slots in the anchor. A suture engagedin the anchor has its ends affixed to posts extending from the driverhandle. The Cerier et al. system suffers from the disadvantage that thedriver does not accommodate sutures having preattached needles. Thus,use of this system requires threading the suture into a needle, atime-consuming procedure for the surgeon.

Another suture anchor installation system is shown in U.S. Pat. No.5,002,550 to Li. The Li system includes a suture anchor having anormally curved barb capable of being elastically deformed to asubstantially straight configuration. The suture anchor engages a suturehaving a pair of surgical needles attached to its ends. The installationtool is adapted to receive the surgical needles and a pair of groovesformed in the tool's outer surface. The tool additionally provides amember for selectively covering and uncovering the needles received inthe grooves. The Li suture anchor installation system uses shape-memoryalloys to fabricate the suture anchors. Such materials are notbioabsorbable. Additionally, the normally curved barb of the Li systemprotrudes from the installation tool during positioning of the anchor.

Yet another suture anchor installation system is disclosed in U.S. Pat.No. 5,354,298 to Lee et al. The suture anchor installation systemincludes a suture anchor assembly engaged with a suture anchor insertiontool. The suture anchor assembly features a two-piece suture anchor forinsertion into a predrilled hole in a bone and at least one suturehaving at least one surgical needle affixed thereto. The two-piecesuture anchor has a setting pin slidably engaged within an engagementmember having barbed legs expandable in response to proximal movement ofthe setting pin. The suture anchor insertion tool includes a bodyportion and a distally extending shaft portion. An annular region of thedistal end of the shaft portion engages the legs of the suture anchorengagement member. A channel in the shaft portion aligns with a channelin the body portion to accommodate the suture. Needle-retainingassemblies located on the body portion of the suture anchor insertiontool engage the surgical needle or needles attached to the suture. Thesuture anchor installation tool of the Lee et al. U.S. Pat. No.5,354,298 is packaged in a preloaded condition. The package is opened inthe operating room and the installation tool is removed from the packageand used to apply the suture anchor.

What is needed is an improved system which facilitates implantation ofthe suture anchor into hard tissue such as, e.g., bone.

SUMMARY

A suture anchor installation system is provided herein, the systemincluding a drill and drill guide, an obturator, at least one sutureanchor and a suture anchor installation tool. The suture anchor includesan elongated setting pin at least partially mounted within alongitudinal bore of a socket and slidably movable between a distalfirst position wherein at least a portion of the setting pin is distalto the socket and a proximal second position. A suture is disposedthrough a hole in the setting pin. The socket has at least twoproximally pointing legs which are radially expandable in response tomovement of the setting pin to the proximal second position.

The suture anchor installation tool includes a handle portion includinga spring, and an elongated operating portion. The operating portionincludes a sheath tube having an axial bore and distal and proximalends, and an inner rod slidably disposed within the bore of the sheathtube. The inner rod is fixedly mounted to the handle, while the sheathtube is movably mounted to the handle, the sheath tube being movablewith respect to the handle between a distal position and a proximalposition, and being resiliently biased to the distal position by thespring. Application of a proximally directed force of sufficientmagnitude to the distal end of the sheath tube causes the sheath tube tomove to the proximal position against the biasing force of the spring.

In the initial configuration the suture is held taut by the installationtool, which also includes at least one pinch means for releasablyholding a suture, the pinch means frictionally holding the suture whenthe sheath tube is in the distal position and releasing the suture inresponse to movement of the sheath tube to the proximal position. Thepinch means is of a plate and a member having at least one leg inopposing relation to the plate, the leg being biased toward the plate tohold a suture therebetween when the sheath tube is in the distalposition, and the leg resiliently moving away from the wall in responseto movement of the sheath tube to the proximal position.

Also disclosed herein is a method for employing the suture anchorinstallation system to apply a suture anchor to a bone, mass.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are described below with reference to the drawingswherein:

FIG. 1 is a side view of a suture anchor for use in the currentdisclosure

FIG. 2 is a perspective view of the setting pin of the suture anchorwith a suture disposed therethrough;

FIG. 3 is an exploded view showing the suture retained by the sutureanchor;

FIG. 4 is a perspective view of the suture anchor installation tool;

FIG. 5 is an exploded view of the suture anchor installation tool withsuture anchor and needles;

FIG. 6 and 7 are perspective views illustrating positioning of thesuture anchor at the distal end of the plunger rod;

FIG. 8 is a perspective view illustrating the positioning of the sutureanchor at the distal end of the installation tool;

FIG. 9 is a partial cut away exploded perspective view of the handleportion of the suture anchor installation tool;

FIG. 10 is a top view of the handle portion of the suture anchorinstallation tool;

FIG. 11 is a side sectional view of the handle portion of the sutureanchor installation tool;

FIG. 12 is a perspective view of a cannula;

FIG. 13 is a perspective view of an obturator;

FIG. 14 is an exploded perspective view of the drill bit and drillguide;

FIG. 15 is a sectional view showing placement of the obturator and drillguide in the cannula;

FIGS. 16 to 19 are sectional views sequentially illustrating the methodof drilling a hole in bone and the placement of the suture anchortherein;

FIG. 20 is a top view of the handle portion of the suture anchorinstallation tool showing release of the suture;

FIGS. 21 and 22 are sequential side sectional views illustrating settingof the suture anchor; and

FIGS. 23 and 24 are perspective views illustrating actuation of thesuture anchor to expand the legs.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The suture anchor installation system described herein is provided forsecuring a suture to bone. The suture can be used to attach soft tissueor a prosthetic device to the bone. As used herein, the term "softtissue" refers to all of the non-bony tissues within an organismincluding, but not limited to, muscle, cartilage, skin, tendons,ligaments, etc. The term "prosthetic device" refers to any articleimplanted in the body including, but not limited to, artificialligaments, muscles, joints, etc.

The suture anchor installation system can be used in minimally invasivesurgical procedures. In such procedures the operating instrumentation isdeployed through a cannula inserted through a small incision or openingin a wall of body tissue (e.g. the skin and underlying tissue), ordirectly through the incision or opening itself. Such procedures includelaparoscopic, endoscopic, and arthroscopic surgical operations. Inoperations where, for example, a body cavity is insufflated to provide aclear operating field, gaseous seals are usually employed to prevent theinflow or egress of fluids into or out from the operating site. Itshould be understood that the suture anchor installation system is notlimited to minimally invasive procedures, and can be used in opensurgical procedures as well.

The suture anchor installation system described herein includes a sutureanchor assembly retained in a suture anchor insertion tool. The sutureanchor assembly features a two-piece suture anchor for insertion into apre-drilled hole in bone and at least one suture having at least onesurgical needle affixed thereto. The two-piece suture anchor includes asetting pin slidably engaged within an expandable engagement memberwhich grips the sides of the hole which has been drilled in the bone. Ina preferred embodiment, this engagement member is an expandable socket,which includes an apertured body portion having at least two barbed legsextending proximally therefrom. The legs are radially expandable inresponse to proximal movement of the setting pin. Suture anchorssuitable for use in the suture anchor installation system describedherein are described in U.S. Pat. No. 5,354,298. The suture can be"double-armed", i.e. a needle can be attached to each of the two ends ofthe suture to facilitate knotting the suture and securing the softtissue to the bone.

More particularly, referring now to FIGS. 1 to 3, a preferred two-piecesuture anchor 10 is illustrated. Preferably, the suture anchor 10 isfabricated from a synthetic bioabsorbable polymeric resin such aspolymers of glycolide, lactide, caprolactone, p-dioxanone, trimethylenecarbonate and physical and/or chemical combinations thereof. The sutureis preferably a size 2 suture formed of Dacron. However, it isanticipated that the suture may also be formed from a syntheticbioabsorbable polymeric resin.

The suture anchor 10 includes a socket 11 for insertion distally into apre-drilled hole in bone or hard tissue. The socket has a body portion12 terminating in an annular distal end surface 13 which acts as a stopsurface as discussed below, an axially extending aperture 14, and atleast two (preferably four) legs 15 extending proximally from the bodyportion 12. Legs 15 are normally radially expandable in response tomovement of a setting pin 20 slidably disposed within the axiallyextending aperture 14. Setting pin 20 has a suture attachment featureand is movable between a distal position with respect to socket 11wherein socket legs 15 are not expanded, and a proximal position withrespect to the socket 11 wherein the socket legs 15 are urged to aradially spread-out configuration.

More particularly, setting pin 20 includes a shaft portion 22, a taperedtip 23 with preferably a frustoconical shape and a proximal facingabutment surface 26, and a transverse aperture 21 near the distal endfor receiving a suture 30. Proximal end 25 is rounded and acts as acamming surface. Setting pin 20 also includes two longitudinal notches24 extending along shaft portion 22 through which suture 30 is disposed.

Proximally extending legs 15 of socket 11 include barbs 16 on theirouter surface and an inwardly inclined inner surface 17. When settingpin 20 is moved proximally from its initial distal-most position (i.e.by pulling suture 30), the rounded proximal end 25 of the shaft portioncams against inner surface 17 and thereby urges legs 15 to expandradially outward. At the most proximal position of setting pin 20,abutment surface 26 of tapered tip 23 contacts distal end surface 13 ofthe socket. The Setting pin 20 is thereby stopped from further proximalmovement. A matching non-circular cross section of the setting pin andthe socket aperture may be employed to prevent suture interference withthe setting action by preventing free rotation of the setting pin withinthe axial aperture of the socket and by locating the suture between legs15 of socket 11.

Referring now to FIGS. 4 and 5, the suture anchor installation systemincludes an installation tool 200 having an elongated operating portion201 and a handle portion 202. The elongated operating portion 201includes an outer sheath tube 250 and a plunger rod 260.

Sheath tube 250 is slidably connected to handle 210 and has an axialbore 254, a distal end 251 with lengthwise slots 252 positioned in thevicinity of the distal end 251, and a proximal end 253. The distal endof the sheath tube acts as the primary support for the suture anchor 10.Referring to FIGS. 4 and 8, slots 252 provide access for suture 30 toexit from the interior of bore 254 and extend along the outer surface ofsheath tube 250 to handle 210. Referring again to FIG. 5, the proximalend 253 of sheath 250 tube abuts a cam cap 230, the function of which isexplained below. Longitudinal slot 256 in the sheath is adapted toreceive plunger pin 245 and acts as a motion limiter, as explainedbelow.

Referring to FIGS. 5-7, plunger rod 260 is slidably disposed within bore254 of sheath tube 250, and includes a distal end portion 261 whichincludes opening 267 to releasably engage the proximal end portion oflegs 15 of the suture anchor 10, and two slots 262 which permit passagetherethrough of the suture 30. Notches 263 extend longitudinally fromthe proximal ends of slots 262 to facilitate the doubling back of suture30 and allow the suture to extend distally outward and through slots 252in the sheath tube (See, FIG. 8) Proximal end portion 264 includesnotches 265 which are engaged by a plunger retainer block 280 (FIG. 7).Plunger retainer block 280 is received into a plunger retainer frame 219in the interior chamber 213 of handle 210, and fixedly connects plungerrod 260 to handle 210. Plunger rod 260 includes a lateral aperture 266to receive plunger pin 245. Plunger pin 245 extends laterally into slot256 of sheath tube 250 to limit the relative longitudinal motion betweenplunger rod 260 and sheath tube 250. For example, if outer sheath tube250 moves proximally with respect to plunger rod 260, plunger pin 245abuts the distal edge of slot 256 after sheath tube 250 has moved acertain distance. Further relative movement is thereby prohibited inthat direction.

Referring to FIGS. 5-11, handle portion 202 includes a handle 210, whichhas, inter alia, a body portion 211 serving as a hand grip, a fingerrest 212, and a cover plate 225. Body portion 211 and cover plate 225define an interior chamber 213. Longitudinal aperture 222 extendsthrough nose portion 239 of handle body portion 211 and is adapted toreceive sheath tube 250 and plunger rod 260. The nose portion 239 alsoincludes a Y-shaped notch 229 which serves as a suture track. That is,suture 30 extends along sheath 250 from slot 252 to interior chamber 213and is disposed through notch 229 such that one length of suture 30passes through one branch of Y-shaped notch 229 and the other length ofthe suture 30 passes through the other branch of Y-shaped notch 229.

Handle body portion 211 includes lengthwise spaced apart needle parkplates 214 having needle retaining notches 215. Notches 215 are adaptedto releasably hold a surgical needle in a snap fit arrangement. Needlepark plates 214 are preferably parallel to each other each having twosets of notches such that at least two needles 50 can be releasably heldby the plates. As can be seen, the needles extend laterally across thetop of plates 214, each needle being held in one set of notches 215 ineach plate 214.

Guide plates 216 are preferably oriented parallel to the needle parkplates 214 and provide a guide surface for the suture lengths 30entering interior chamber 213 from Y-shaped notch 229. The guide platesalso stabilize the needles 50 to allow for closer placement.

Pinch plates 217 are spaced apart from each other and the space betweenthem provides a reception area to receive pinch block 270. The suturelengths 30 are guided by guide plates 216 to enter the space betweenpinch plates 217 and pinch block 270 (discussed below). Pinch plates 217each have a curved portion 218 which provides a suture pinch area.

Needle park plates 214, guide plates 216, pinch block plates, buttressplates 220 and 221 (discussed below), and plunger block retainer frame219, are features which may be integrally fabricated as part of handlebody 211 by, for example, molding body portion 211 from a suitablematerial, such as polycarbonate, acrylics, or other synthetic polymericresins. Handle body 211 also includes apertures 224 to receive alignmentrods 228 in the cover.

Pinch block 270 is a single piece generally U-shaped body which includesparallel legs 272 extending distally from a proximal wall 271 andterminating in opposing jaws 274. Jaws 274 define between them a spacefor the reception of cam cap 230. Legs 272 are resiliently movabletoward or away from each other to vary the distance between jaws 274. Aridge 273 extends vertically (as shown) on an outer surface of each leg272, the ridge being received into curved suture pinch areas 218 ofpinch plates 217. When legs 272 are biased outward, ridges 273 andrespective suture pinch areas 218 close upon the suture portion disposedbetween them, thereby frictionally holding the suture.

Pinch block 270 also includes an axial aperture 277 in proximal wall 271through which plunger rod 260 is disposed. The distal surface 278 of theproximal wall provides an abutment surface for helical compressionspring 240, which is positioned between legs 272. Pinch block 270 issecurely retained in interior chamber 213 between buttress plates 220and guide plates 216.

Cam cap 230 includes a single piece structure including a rectangulardistal portion 231 having an internal cylindrical bore 232, and acylindrical proximal portion 233 having bore 234. Cam cap 230 possessesan exterior proximally facing surface 235 which provides an abutment forspring 240. Also, a distally facing annular surface 236 in internalcylindrical bore 232 provides an abutment for proximal end 253 of thesheath tube. Thus, sheath tube 250 is inserted into cylindrical bore232, and spring 240 is mounted around proximal portion 233. The plungerrod 260 extends through bore 234.

Cam cap 230 is initially positioned such that distal portion 231 isbetween jaws 274 of pinch block 270, thereby biasing legs 272 outward tofrictionally secure suture lengths 30 between ridges 273 and pinch areas218 of pinch plates 217. When sheath tube 250 is moved proximally, camcap 230 is forced against the biasing action of compression spring 240into the space between legs 272. This allows legs 272 to resilientlybend inward to a degree sufficient to release the suture lengths 30.Also, because jaws 274 move inwardly, cam cap 230, once past the jaws,cannot return distally to its initial position between the jaws. Thus,once the outer sheath is retracted beyond a predetermined distance itremains in the retracted configuration and cannot move distally forwardto its initial position.

Plunger retainer block 280 includes leg members 281 which engage notches265 in plunger rod 260. Plunger retainer block 280 is adapted to fitinto retainer frame 219 so as to secure the proximal end portion 264 ofplunger rod 260 to handle 210.

Buttresses 220 are plates which extend longitudinally along sideretainer frame 219. Buttresses 221 are plates which extend laterallyfrom the inner wall of body grip 211 in the vicinity of the pinch plates217. Both serve as reinforcements and are preferably an integral part ofhandle body 211.

Referring to FIG. 9, cover 225 is a flat plate which includes distallyextending alignment rods 228, resilient hooks 227, and an open windowarea 226. Alignment rods 228 are adapted to fit into aperture 224 in thebody grip. The hooks 227 are adapted to engage catches 223 in the bodygrip in a snap-fit manner.

Referring now to FIGS. 12 to 14, the suture anchor installation systemincludes a drill guide 110, drill bit 140, and obturator 130, alladapted to fit within the bore of a standard cannula 150. Means isprovided herein for drilling a hole in bone. The drilling means includesthe drill guide 110 and the drill bit 140.

Referring to FIG. 14, drill guide 110 provides precise positioning ofthe drill for drilling a hole for the suture anchor into the mass ofbone tissue, and is a tubular body 111 having teeth 113 for grippingbone tissue at its distal end 115, and, optionally, flat surfaces 114spaced apart from the flared proximal end portion 116. Axial bore 117 inthe drill guide is adapted to receive a drill bit 140, discussed below.At least one, and preferably two or three, openings 112 in the vicinityof the distal end 115 permit the escape of bone fragments and shavingsduring the drilling operation and also permit visualization of the drillbit placement by the surgeon. The flat surfaces 114 are adapted toengage slot 125 in the forked end portion 124 of a handle 120. Drillguide 110 is preferably fabricated from a biocompatible metal such asstainless steel alloy.

Drill guide handle 120 is fixedly attached to drill guide 110 tofacilitate the surgeon's handling of drill guide 110. Drill guide handle120 is a single piece composed of a grasping plate 121 having a wide endportion 122 adapted to facilitate manual gripping by the surgeon. Theforked end portion 124 includes two parallel spaced apart prongs 126which define a slot 125 between them into which the drill guide 110 isengaged at the flat surfaces 114. The forked end portion 124 isconnected to the grasping plate 121 at angled bend 123.

Drill bit 140 is used to create a hole of predetermined diameter in themass of bone tissue. Drill bit 140 is a single piece member having adistal drilling tip 141, a shaft 146 having a relatively wide distalportion 142, a relatively narrow mid portion 143, and a proximal portion144. A shank 145 extends proximally from portion 144 of shaft 146 and isadapted to engage the chuck of a drilling machine (not shown). Drillingmachines suitable for use in rotating the drill bit are well known andavailable to those with skill in the art. The drill bit 140 is adaptedto fit into bore 117 of drill guide 110 and to be able to rotatetherein.

Referring to FIG. 13, obturator 130 is part of the suture anchorinstallation system and includes a shaft 131 having a bevelled tip 132with rounded point 133. A knurled knob 134 facilitates its handling anduse to create a puncture opening in the soft body tissue overlying thebone with minimal damage to the body tissue.

Referring to FIG. 12, a cannula 150 suitable for use in the presentsystem is shown. Such cannulas are well known in the art and widelyavailable.

Referring to FIGS. 15 to 18 the use of the suture anchor installationsystem is illustrated.

First, an incision 71 is created in the skin and access to body tissue70 surrounding the bone at the operating site is achieved. Cannula 150is inserted into the incision 71.

Obturator 130 is placed within the drill guide 110 and both are insertedthrough cannula 150 and into body tissue 70 to create a passagewaythrough the soft tissue to access the bone. (FIGS. 15, 16). Obturator130 is then removed leaving drill guide 110 inserted through thepassageway in the soft tissue with the distal teeth 113 placed againstthe bone at the site to be drilled.

The drill bit 140 is then inserted in the drill guide and is used tocreate a hole 74 in the bone 73. (FIG. 17)

Referring to FIG. 18, the drill bit and drill guide 110 are removed fromcannula 150 and the distal end of the installation tool is then insertedinto the cannula 150. Optionally, drill guide 110 can be left in placeand the installation tool can be positioned within drill guide 110. Theinstallation tool 200 is positioned such that suture anchor 10 isaligned with hole 74. The hole diameter is large enough to receivesuture anchor 10 but smaller than the diameter of sheath tube 250.Referring to FIGS. 19, and 20, as the surgeon applies a distallydirected force to installation tool 200 to advance suture anchor 10 intothe hole in the bone, the adjacent bone structure pushes back on sheathtube 250. This action pushes cam cap 230 into the space between legs 272of the pinch block, which spring inward, thereby locking the cam cap ina proximal position and releasing suture 30 from the pinch plate 217such that suture 30 is no longer held in its initially taut manner. Theinstallation tool 200 can then be withdrawn from the cannula 150, (FIG.21) leaving the suture anchor 10 in place within hole 74. Referring toFIGS. 22, 23, and 24, the surgeon then removes needles 50 and suture 30from handle 210 of the installation tool and pulls on the suture toexpand the legs of the suture anchor (FIG. 24) and fix it securelywithin the bone. Optionally, the surgeon can actuate the suture anchor10 prior to removal of installation tool 200 from the cannula, whichapproach may advantageously hold the suture anchor within the hole asthe suture anchor is actuated. The suture lengths 30 can be tied tosecure the soft tissue or prosthetic implant to the bone. For example,several suture anchors can be applied to the bone and the sutures of thevarious anchors can be knotted together to tie down the soft tissue.

It will be understood that various modifications may be made to theembodiments disclosed herein. The above description should not beconstrued as limiting, but merely as exemplifications of preferredembodiments. Those skilled in the art will envision other modificationswithin the scope and spirit of the claims appended hereto.

What is claimed is:
 1. An apparatus for installing a suture anchor,which comprises:a) a handle portion having at least one pinch means forreleasably holding a suture; and b) an elongated portion attached tosaid handle portion, and including a sheath tube having an axial boreand distal and proximal ends, and an inner rod disposed within the boreof the sheath tube, the inner rod being fixedly mounted to the handle.2. The apparatus of claim 1 wherein the inner rod has a distal endportion having an opening to releasably hold a suture anchor.
 3. Theapparatus of claim 1 wherein the handle includes at least one needlepark.
 4. The apparatus of claim 1 wherein the pinch means includes apair of spaced apart arms each being movable between an outward positioninto close proximity to a respective one of a corresponding pair ofplates for frictionally holding a suture therebetween and an innerposition wherein the suture is released.
 5. The apparatus of claim 1further including a plate disposed within the handle portion and atleast one leg in opposing relation to the plate, the leg being biasedtoward the plate to hold a suture therebetween.
 6. The apparatus ofclaim 5 further including a suture anchor with a suture connectedthereto wherein the suture is disposed longitudinally along an outsidesurface of the sheath tube in an initially taut configuration, a portionof the suture being disposed between the plate and the at least one leg.7. The apparatus of claim 1 further including a suture anchor whichincludes an elongated setting pin at least partially mounted within alongitudinal bore of a socket and slidably movable between a distalfirst position wherein at least a portion of the setting pin is distalto the socket and a proximal second position, the socket having at leasttwo proximally pointing legs which are radially expandable in responseto movement of the setting pin to said proximal second position, and thesetting pin having a suture connected thereto.
 8. A system forinstalling a suture anchor, which comprises:a) means for drilling a holeof predetermined diameter into bone tissue; b) a suture anchor having alength of suture attached thereto; c) a suture anchor installation toolwhich includesi) a handle portion; and ii) an elongated portion attachedto said handle portion, and including a sheath tube having an axial boreand distal and proximal ends, and an inner rod disposed within the boreof the sheath tube, the inner rod being fixedly mounted to the handle,and the sheath tube being mounted to the handle and having a portionwith an outer diameter greater than the diameter of the hole in thebone.
 9. The system of claim 8 wherein the suture anchor is releasablymounted to a distal end portion of the rod.
 10. The system of claim 8wherein the sheath tube includes at least one longitudinal slot and theinner rod includes a pin extending into the longitudinal slot of thesheath tube.
 11. The system of claim 8 wherein the handle includes atleast one needle park.
 12. The system of claim 8 wherein the means fordrilling a hole in bone includes a guide tube and a drill bit movablydisposed with the guide tube.
 13. The system of claim 8 furtherincluding an obturator.
 14. The system of claim 8 wherein the sutureanchor includes an elongated-setting pin at least partially mountedwithin a longitudinal bore of a socket and slidably movable between adistal first position wherein at least a portion of the setting pin isdistal to the socket and a proximal second position, the socket havingat least two proximally pointing legs which are radially expandable inresponse to movement of the setting pin to said proximal secondposition.
 15. A method for applying a suture anchor to bone,comprising:a) drilling a hole of predetermined size into a mass of bonetissue; b) providing a suture anchor having a length of suture connectedthereto; c) providing a suture anchor installation tool whichincludes:i) a handle portion; and ii) an elongated portion attached tosaid handle portion, and including an sheath tube having an axial bore,and distal and proximal ends, and an inner rod disposed within the boreof the sheath tube, the inner rod being fixedly mounted to the handleand having a distal end portion to which the suture anchor is releasablyengaged, and the sheath tube being mounted to the handle and having aportion with an outer diameter greater than the diameter of the hole inthe bone; d) positioning the distal end of the sheath tube inconjunction with the hole in the bone such that the suture anchor isaligned with the hole in the bone; e) applying distally directed forceto the installation tool, thereby advancing the suture anchor into thehole in the bone.
 16. The method of claim 15 further comprising the stepof deploying the suture anchor in the hole.
 17. The method of claim 16wherein the suture anchor includes a setting pin connected at leastpartially mounted within a longitudinal bore of a socket and slidablymovable between a distal first position wherein at least a portion ofthe setting pin is distal to the socket and a proximal second position,the socket having at least two legs which are radially expandable inresponse to movement of the setting pin to said proximal secondposition, the step of actuating the suture anchor comprising moving thesetting pin to its proximal second position.
 18. The method of claim 17wherein the setting pin is moved to its proximal position by applying aproximally directed pulling force to the suture sufficient to move thesetting pin to the proximal second position.
 19. The method of claim 15further including the steps of providing an obturator and forming anopening in soft body tissue in the vicinity of the bone mass prior todrilling a hole in the bone and inserting a cannula into the opening inthe soft tissue.
 20. The method of claim 19 wherein the step of drillinga hole of predetermined size into a mass of bone tissuecomprises:placing a drill guide tube through the opening in the softtissue formed by the obturator, positioning the drill guide tube withrespect to the bone, inserting a drill bit through the drill guide tubeinto contact with the bone tissue, and drilling the bone tissue with thedrill bit.